Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

A projector having a first lens array with a plurality of first lenses in
a plane substantially orthogonal to an optical axis of the light beam
from a light source that divides the light beam into a plurality of
partial light beams, a second lens array having a plurality of second
lenses corresponding to the plurality of first lenses, and a polarization
converter that is disposed on a light beam emitting-side of the first
lens array. A focal position in a first direction of the first lens is
set in the vicinity of the second lens array in the optical direction of
the light beam irradiated from the first lens. A focal position in the
second direction of the first lens is set in the vicinity of the
polarization converter in the optical direction of the light beam
irradiated from the first lens.

Claims:

1. A projector comprising:a light source;an optical modulator that
modulates a light beam irradiated from the light source in accordance
with image information;a first lens array having a plurality of first
lenses in a plane substantially orthogonal to an optical axis of the
light beam irradiated from the light source;a second lens array having a
plurality of second lenses corresponding to the plurality of first lenses
of the first lens array; anda polarization converter disposed on a light
beam emitting-side of the first lens array, the polarization converter
including:a polarization separating layer;a reflection layer; anda phase
layer disposed at a position corresponding to either the polarization
separating layer or the reflection layer, whereinthe first lens had a
first focal position in a first direction and a second focal position in
a second direction, the first focal position being closer to the second
lens array than the polarization converter in the optical axis direction
of the light beam irradiated from the first lens, and the second focal
position being closer to the polarization converter than the second lens
array in the optical axis direction of the light beam irradiated from the
first lens,the first direction is a lengthwise direction of the
polarization separating layer in a plane substantially orthogonal to the
optical axis of the light beam irradiated from the light source, andthe
second direction is orthogonal to the optical axis of the light beam
irradiated from the light source and the first direction, the
polarization separating layer and the reflection layer being alternately
arranged in the second direction.

2. The projector according to claim 1, further comprising:a
color-separating optical system that separates the light beam irradiated
from the light source into a plurality of color light beams, the optical
modulator being provided for each of the plurality of color light beams,
and the optical modulators being disposed on each optical path of the
plurality of color light beams; anda color-combining optical device that
combines the plurality of color light beams irradiated from the optical
modulators, the color-combining optical device being provided on the
downstream of the optical path of the optical modulators.

3. The projector according to claim 1, wherein the first lens is a toric
lens.

4. The projector according to claim 2, wherein the first lens is a toric
lens.

5. A projector comprising:a light source;an optical modulator that
modulates a light beam irradiated from the light source in accordance
with image information;a first lens array having a plurality of first
lenses in a plane substantially orthogonal to an optical axis of the
light beam irradiated from the light source, the first lens is a toric
lens;a second lens array having a plurality of second lenses
corresponding to the plurality of first lenses of the first lens array;
anda polarization converter disposed on a light beam emitting-side of the
first lens array, the polarization converter including:a polarization
separating layer;a reflection layer; anda phase layer disposed at a
position corresponding to either the polarization separating layer or the
reflection layer.

6. The projector according to claim 5,wherein the toric lens has focal
positions in a first direction and in a second direction being orthogonal
to the first direction,the first direction is the lengthwise direction of
the polarization separating layer in a plane substantially orthogonal to
the optical axis of the light beam irradiated from the light source.

7. The projector according to claim 6,wherein the polarization separating
layer and the reflection layer are alternately arranged in the second
direction.

Description:

[0001]This is a Continuation of application Ser. No. 11/703,146 filed on
Feb. 7, 2009. The disclosure of the prior application is hereby
incorporated by reference in its entirety. The entire disclosure of
Japanese Patent Application No. 2006-42955, filed Feb. 20, 2006, is
expressly incorporated by reference herein.

BACKGROUND

[0002]1. Technical Field

[0003]The present invention relates to a projector that includes a light
source, an optical modulator that modulates a light beam irradiated from
the light source in accordance with image information to form an image
and a projection optical system that projects the formed image.

[0004]2. Related Art

[0005]There have been known projectors that form an optical image in
accordance with image information and project the optical image on a
screen or the like in an enlarged manner. Among such projectors, there is
known a projector that includes a light source, an optical modulator that
modulates a light beam irradiated from the light source in accordance
with image information and a projection lens that projects the modulated
light beam as an optical image.

[0006]Recently, so-called three-panel projectors have been proposed, which
can form an image with enhanced image quality and color reproducibility.
Such a three-panel projector includes: a color-separating optical system
that separates a light beam irradiated from a lamp as a light source into
three color light beams of red (R), green (G) and blue (B); a plurality
of liquid crystal panels as optical modulators which modulate the
incident color light beams in accordance with image information; and a
color-combining optical device that combines the color light beams
modulated by the liquid crystal panels to form an optical image.

[0007]Note that it is necessary to uniformly illuminate an image formation
area of an optical modulator such as a liquid crystal panel. Accordingly,
there has been known a projector with an integrator illuminating optical
system that divides a light beam irradiated from the lamp into a
plurality of partial light beams, superpose the partial light beams on
the image formation areas of the optical modulators and uniformly
illuminate the image formation areas (see, for example,
JP-A-2005-234126).

[0008]The projector disclosed in the document includes as the integrator
illuminating optical system a first lens array having a plurality of
small lenses arranged in a matrix form, a second lens array having a
plurality of small lenses respectively corresponding to the plurality of
small lenses of the first lens array, a polarization converter that
aligns polarization directions of light beams respectively irradiated
from the plurality of small lenses of the second lens array and a
superposing lens that superposes the incident light beams from the
polarization converter on the image formation areas of the liquid crystal
panels, each component being in a plane orthogonal to the optical axis of
the light beam irradiated from the lamp. The integrator illuminating
optical system uniforms a light amount on an illumination region of the
light beam irradiated from the lamp, so that the image formation areas of
the liquid crystal panels can be uniformly illuminated.

[0009]However, a light emitting portion of the light source lamp of such a
projector may be moved from the middle of the electrodes of the light
source lamp. When the light emitting portion is moved after optical
components of the projector are positioned and fixed, a formed optical
image may contain color unevenness.

[0010]To avoid the problem, there have been demands for a projector that
can reduce luminance unevenness on the image formation area of the
optical modulator even when the light emitting portion of the light
source lamp is moved substantially from the middle of the electrodes
after the positioning and fixation of the optical components.

SUMMARY

[0011]An exemplary aspect of the present invention provides a projector
which reduces luminance unevenness on an image formation area even when a
light emitting portion of a light source lamp is moved after positioning
and fixation of an optical component.

[0012]A projector of an exemplary aspect of the present invention includes
a light source, an optical modulator which modulates a light beam
irradiated from the light source in accordance with image information to
form an optical image and a projection optical system which projects the
formed optical image. The projector includes an integrator illuminating
optical system which equalizes the light beam irradiated from the light
source and uniformly illuminates an image formation area of the optical
modulator. The integrator illuminating optical system includes: a first
lens array having a plurality of first lenses in a plane substantially
orthogonal to an optical axis of the light beam irradiated from the light
source and divides the light beam into a plurality of partial light beams
by the plurality of first lenses; a second lens array having a plurality
of second lenses corresponding to the plurality of first lenses of the
first lens array; and a polarization converter which is disposed on a
light beam emitting-side of the first lens array and aligns a
polarization direction of the light beam irradiated from the first lens
array into a substantially uniform type. The polarization converter
includes at least one polarization separating layer, at least one
reflection layer and a phase layer which is disposed at a position
corresponding to either the polarization separating layer or the
reflection layer. The lengthwise direction of the polarization separating
layer in a plane substantially orthogonal to the optical axis of the
light beam irradiated from the light source is defined as a first
direction. The polarization separating layer transmits light having one
polarization direction of an incident light beam and reflects light
having another polarization direction. The polarization separating layer
and the reflection layer are alternately arranged in a second direction.
The second direction is orthogonal to the optical axis of the light beam
irradiated from the light source and the first direction. The reflection
layer reflects the polarized light reflected by the polarization
separating layer into a common direction to that of the polarized light
passed through the polarization separating layer. The phase layer
converts the polarization direction of the incident polarized light into
another polarization direction. A focal position in the first direction
of the first lens is set in the vicinity of the second lens array in the
optical axis direction of the light beam irradiated from the first lens.
A focal position in the second direction of the first lens is set in the
vicinity of the polarization converter in the optical axis direction of
the light beam irradiated from the first lens.

[0013]According to the exemplary aspect of the invention, even when the
light emitting portion is moved in the light source, luminance unevenness
on the image formation area of the optical modulator can be reduced.

[0014]Specifically, since the focal position in the second direction of
the plurality of first lenses of the first lens array is set in the
vicinity of the polarization converter in the optical axis direction of
the light beam irradiated from the first lens, the light beam irradiated
from the first lens is incident on the polarization converter in a narrow
illumination region. When the light emitting portion of the light source
is moved in the second direction in which the polarization separating
layer and the reflection layer of the polarization converter are aligned,
substantially no light of the partial light beams generated from the
light irradiated from an end position of the light emitting portion on
the movement direction side and transmitted through the first lens is
incident on the light incident surface of the polarization converter,
while substantially all the light of the partial light beams generated
from the light irradiated from a position in the vicinity of the center
of the light emitting portion and transmitted through the first lens is
incident on the light incident surface of the polarization converter.
That is, the partial light beams generated from each light irradiated
from different positions in the light emitting portion are not incident
on the light incident surface at different rates. Substantially all the
light of certain partial light beams out of the partial light beams
generated from the light irradiated from different positions in the light
emitting portion is incident on the light incident surface of the
polarization converter.

[0015]Accordingly, substantially all the light of the partial light beams
generated from the light irradiated from a certain position in the light
emitting portion is superposed and incident on the image formation area
of the optical modulator, thereby preventing a large difference in
illumination intensity (luminance) between the one end position side and
the other end position side in the second direction of the image
formation area, compared with the case in which the partial light beams
of which light is partially reduced on the one end position side in the
second direction is superposed on the image formation area of the optical
modulator. Hence, the luminance unevenness can be reduced on the image
formation area of the optical modulator.

[0016]Since the focal position in the first direction of the first lens is
set in the vicinity of the second lens array on the optical axis of the
light beam irradiated from the first lens, the partial light beams
irradiated from the first lens are incident on a narrow illumination
region of a corresponding second lens on which the partial light beams
are to be incident. When the light emitting portion of the light source
is moved in the first direction orthogonal to the second direction in a
plane orthogonal to the optical axis of the light beam irradiated from
the light source, the partial light beams generated from the light
irradiated from a position on an outer side of the light emitting portion
in the movement direction are not incident on the corresponding second
lens. Incident on the corresponding second lens are only the partial
light beams generated from the light irradiated from a position in the
vicinity of the center of the light emitting portion and from an end on
the other side which is opposite to the movement direction.

[0017]Accordingly, similarly to the above-described case, substantially
all the partial light beams generated from the light irradiated from
different positions in the light emitting portion are not incident on the
corresponding second lens at different rates, but substantially all the
light of certain partial light beams out of the partial light beams
generated from each light irradiated from different positions in the
light emitting portion is incident on the corresponding second lens. As
described above, the partial light beams incident on the corresponding
second lens are superposed on the image formation area of the optical
modulator by a superposing lens, thereby preventing a large difference in
illumination intensity (luminance) between the one end position side and
the other end position side in the first direction of the image formation
area, compared with the case in which the partial light beams of which
light is partially reduced on the one end position side in the first
direction is superposed on the image formation area of the optical
modulator. Hence, the luminance unevenness can be reduced on the image
formation area.

[0018]According to an exemplary aspect of the invention, the projector may
preferably include: a color-separating optical system which separates the
light beam irradiated from the integrator illumination optical system
into a plurality of color light beams. The optical modulator is provided
for each of the plurality of color light beams, the optical modulators
being disposed on each optical path of the plurality of color light
beams. The projector may further include: at least one color-combining
optical device which is provided on the downstream on the optical path of
the optical modulators. The color combining optical device combines the
plurality of color light beams irradiated from the optical modulators.

[0019]An example of such a color-separating optical system is a system
with a dichroic mirror that transmits a color light beam of a
predetermined wavelength and reflect a color light beam of the other
wavelength and with a total reflection mirror that totally reflects the
incident light beam. An example of such a color-combining optical device
is a device with a cross dichroic prism or a plurality of dichroic
mirrors.

[0020]The projector according to the exemplary aspect of the invention, in
which the color light beams separated by the color-separating optical
system are modulated by the plurality of optical modulators and the
modulated color light beams are combined into an optical image by the
color-combining optical device, can form a color image with reduced color
unevenness.

[0021]When the color-separating optical system includes the dichroic
mirror and the total reflection mirror, the light beams incident on the
color-separating optical system are repeatedly reflected by the mirrors
in the color-separating process of the color light beams in accordance
with wavelengths. Hence, as described above, when the position of the
light emitting portion of the light source is moved substantially from
the middle of the electrodes, causing unevenness in illumination
intensity (luminance) in the illumination region of the light beam
irradiated from the light source, a higher side and a lower side of
illumination intensity (luminance) on the image formation area may be not
aligned between the optical modulators. In this case, in the image
passing through the image formation areas and combined by the
color-combining optical device, a higher side and a lower side of the
illumination intensity may differ between an image derived from a certain
color light beam and another image derived from another color light beam,
thereby possibly causing color unevenness on the formed image.

[0022]In contrast, even when the position of the light emitting portion in
the light source is moved, the image formation area is substantially
uniformly illuminated by the integrator illuminating optical system, so
that the luminance unevenness on the image formation area can be reduced
and an image without brightness unevenness can be formed on the image
formation area. Accordingly, by combining the images without brightness
unevenness, an optical image (a color image) can be formed while reducing
color unevenness.

[0023]Hence, color unevenness can be reduced in forming an optical image
even when the plurality of optical modulators for modulating the incident
color light and the color-combining optical system for combining the
color light modulated by the plurality of optical modulators to form an
optical image are provided.

[0024]According to an exemplary aspect of the invention, the first lens is
preferably a toric lens.

[0025]According to the exemplary aspect of the invention, the toric lens
employed as the first lens easily enables the arrangement in which the
first lens has the different focal positions in the first and second
direction. Hence, such arrangement facilitates the manufacturing of the
first lens array and simplifies the structure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]The invention will be described with reference to the accompanying
drawings, wherein like numbers reference like elements.

[0027]FIG. 1 is a schematic illustration briefly showing a structure of a
projector of a first exemplary embodiment of the invention;

[0028]FIG. 2 is a schematic illustration showing a focal position in a
second direction of a first lens of the first exemplary embodiment;

[0029]FIG. 3 is a schematic illustration showing a focal position in a
first direction of the first lens of the first exemplary embodiment;

[0030]FIG. 4 is a schematic illustration showing a structure of a
polarization converter of the first exemplary embodiment;

[0031]FIG. 5 is an illustration showing an optical path of a light beam in
a second direction of a first comparison to the first exemplary
embodiment;

[0032]FIG. 6 is an illustration showing a portion of FIG. 5 in an enlarged
manner;

[0033]FIG. 7 is a graph showing a relation between a movement amount in
the second direction of a light emitting portion and luminance
distribution on a liquid crystal panel of the first comparison to the
first exemplary embodiment;

[0034]FIG. 8 is an illustration showing an optical path of a light beam in
the second direction of the first exemplary embodiment;

[0035]FIG. 9 is an illustration showing a portion of FIG. 8 in an enlarged
manner;

[0036]FIG. 10 is a graph showing a relation between a movement amount in
the second direction of a light emitting portion and luminance
distribution on a liquid crystal panel of the first exemplary embodiment;

[0037]FIG. 11 is a schematic illustration showing a focal position in a
second direction of a first lens of a second exemplary embodiment of the
invention; and

[0038]FIG. 12 is a schematic illustration showing a focal position in a
first direction of the first lens of the second exemplary embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENT(S)

1. First Exemplary Embodiment

[0039]A first exemplary embodiment of the invention will be described
below with reference to the attached drawings.

[0040]1 Structure of Projector 1

[0041]FIG. 1 is a schematic illustration briefly showing a structure of a
projector 1 of the first exemplary embodiment.

[0042]The projector 1 modulates a light beam irradiated from a light
source in accordance with image information to form an optical image and
projects the formed optical image on a screen (not shown) in an enlarged
manner. As shown in FIG. 1, the projector 1 includes an exterior cashing
2, a projection lens 3 as a projection optical device and an optical unit
4.

[0043]In FIG. 1, disposed in the space not occupied by the projection lens
3 and the optical unit 4 in the exterior cashing 2 are a cooling unit
having a cooling fan for cooling the inside of the projector 1, a power
unit for supplying electricity to components in the projector 1, a
control device for controlling the whole projector 1 and the like (all
not shown).

[0044]The exterior cashing 2 is made of synthetic resin substantially in a
rectangular parallelepiped shape as a whole and accommodates the
projection lens 3 and the optical unit 4 as shown in FIG. 1. Although not
shown in the figures, the exterior cashing 2 includes an upper case
forming a top surface, a front surface, a rear surface, right and left
lateral surfaces of the projector 1 and a lower case forming a bottom
surface, the front surface and the rear surface of the projector 1. The
upper case and the lower case are fixed to each other with a screw or the
like.

[0045]The material of the exterior cashing 2 is not limited to synthetic
resin but may be, for example, metal.

[0046]The optical unit 4, which is under control of the control device,
optically processes the light beam irradiated from the light source to
form an optical image (a color image) in accordance with image
information. As shown in FIG. 1, the optical unit 4 extends along the
rear surface and the lateral surface of the exterior cashing 2 in a
substantially L shape.

[0047]The projection lens 3 is a projection optical system that projects
the optical image (the color image) formed by the optical unit 4 on the
screen (not shown) in an enlarged manner. The projection lens 3 may be a
lens set of a plurality of lenses arranged in a cylindrical lens barrel.

[0048]2 Structure of Optical Unit 4

[0049]As shown in FIG. 1, the optical unit 4 includes an illumination
optical device 41, a color-separating optical device 42, a relay optical
device 43, an electrooptical device 44 and an optical component cashing
45 that accommodates the optical components 41 to 44 and supports the
projection lens 3 at a predetermined position in a fixed manner.

[0050]FIG. 2 is a schematic illustration showing the illumination optical
device 41 seen from an upper side. FIG. 3 is a schematic illustration
showing the illumination optical device 41 seen in a horizontal
direction.

[0051]The illumination optical device 41 almost uniformly illuminates an
image formation area of a liquid crystal panel 441 (described later) of
the electrooptical device 44. As shown in FIG. 1, the illumination
optical device 41 includes a light source device 411, a first lens array
412, a second lens array 413, a polarization converter 414 and a
superposing lens 415.

[0052]As shown in FIGS. 1 to 3, the light source device 411 includes a
light source lamp 416 that irradiates a radial light beam, a reflector
417 that reflects the radial light beam irradiated by the light source
lamp 416 to converge the radial light beam at a predetermined position
and a collimating lens 418 that parallelizes the light beam converged by
the reflector 417 relative to an illumination optical axis A.

[0053]The light source lamp 416 includes a silica glass tube. As shown in
FIGS. 2 and 3, the light source lamp 416 includes a tubular spherical
portion 4161 that bulges in a substantially spherical shape at a middle
portion and a pair of sealing portions 4162, 4163 extending in directions
apart from each other from each end of the tubular spherical portion
4161. Note that in FIG. 3, only some components are given numeral
references. In the tubular spherical portion 4161, a discharge space S is
formed in which a pair of electrodes 4164, 4165, mercury, a noble gas and
a small amount of halogen are sealed.

[0054]The light source lamp 416 may be any lamp selected from various
light source lamps capable of emitting light with high brightness such as
a metal halide lamp, a high-pressure mercury lamp and an extra
high-pressure mercury lamp.

[0055]In addition to the pair of electrodes 4164, 4165, inserted in the
pair of sealing portions 4162, 4163 are metal foils 4166, 4167 that are
made of molybdenum and electrically connected to the pair of electrodes
4164, 4165. The pair of sealing portions 4162, 4163 is sealed by a glass
material or the like. Also connected to the metal foils 4166, 4167 are
lead wires 4168, 4169 (electrode-connecting wires) which extend to the
outside of the light source device 411. Applying a voltage on the lead
wires 4168, 4169 generates via the metal foils 4166, 4167 a potential
difference between the pair of electrodes 4164, 4165 to discharge, so
that a light emitting portion D is generated, thereby lighting the
tubular spherical portion 4161 as shown in FIGS. 2 and 3.

[0056]As shown in FIG. 2, the reflector 417 is attached to the sealing
portion 4163 of the light source lamp 416 (on a base end side in the
light beam irradiation direction). The reflector 417 is a
light-transmissive molded article of glass with a reflecting portion 4171
in a concave curved surface shape. A reflecting surface 4172 is provided
on the light source lamp 416 side of the reflecting portion 4171. The
reflecting surface 4172 is formed by metal film deposition on a glass
surface having a rotary ellipsoidal surface shape. The reflector 417 is
an ellipsoidal reflector with the rotary ellipsoidal surface in the first
exemplary embodiment but may be a parabolic reflector with a rotary
parabolic surface. When employing the parabolic reflector, the
collimating lens 418 is omitted.

[0057]The light source lamp 416 in the reflecting portion 4171 of the
reflector 417 is disposed with the center O of the light emitting portion
D in a normal state positioned in the vicinity of a first focal position
of the rotary ellipsoidal surface shape of the reflecting surface 4172 of
the reflector 417. When the light source lamp 416 is turned on, among
light beams irradiated by the light emitting portion D a light beam
irradiated toward the reflector 417 is reflected on the reflecting
surface 4172 of the reflector 417 to be a convergent light beam that is
converged at a second focal position of the rotary ellipsoidal surface.

[0058]As shown in FIG. 2, a sub reflection mirror 416A is provided to the
light source lamp 416. The sub reflection mirror 416A is attached to the
sealing portion 4162 on the other side of the light source lamp 416 (i.e.
to the sealing portion 4162 on the opposite side of the reflector 417
side). A reflecting portion 416A1 of a substantially hemispherical
surface shape is formed on the sub reflection mirror 416A.

[0059]The reflecting portion 416A1 is formed in a substantially cup shape
so as to cover substantially a front half of the tubular spherical
portion 4161 of the light source lamp 416 (the front half on the light
beam irradiation side). A hemispherical reflecting surface 416A2 is
formed on the reflecting portion 416A1 such that an inner surface of the
hemispherical reflecting surface 416A2 curves along the spherical surface
of the tubular spherical portion 4161 of the light source lamp 416.

[0060]By attaching the sub reflection mirror 416A on the light source lamp
416, a light beam radiated toward the front side among the light beams
radiated from the light emitting portion D of the light source lamp 416
is reflected by the sub reflection mirror 416A toward the light emitting
portion D to be incident on the reflector 417 similarly to the light beam
directly irradiated from the light source lamp 416 to the reflecting
surface 4172 of the reflector 417. The light beam is then converged at
the second focal position.

[0061]The light beam converged by the reflector 417 is converted by the
collimating lens 418 into a parallel light substantially parallel to the
illumination optical axis A. Thus, the central axis of the illumination
light beam irradiated from the light source device 411 is aligned with
the illumination optical axis A.

[0062]As shown in FIGS. 2 and 3, the first lens array 412 includes first
lenses 4121 (a plurality of small lenses) arranged in a matrix form in a
plane substantially orthogonal to the illumination optical axis A. The
first lenses 4121 each have a substantially rectangular shape when seen
in the direction of the illumination optical axis A. The first lens 4121
divides the light beam irradiated from the light source device 411 into a
plurality of partial light beams. A focal position of the first lenses
4121 of the first lens array 412 will be described later.

[0063]The second lens array 413 has substantially the same structure as
the first lens array 412. In the second lens array 413, second lenses
4131 (small lenses respectively corresponding to the first lenses 4121)
are arranged in a matrix form (see FIGS. 2 to 4). In cooperation with the
superposing lens 415, the second lens array 413 combines images of the
first lenses 4121 of the first lens array 412 on the image formation area
of the below-described liquid crystal panel 441 of the electrooptical
device 44.

[0064]FIG. 4 is a partially enlarged cross section of the polarization
converter 414.

[0065]As shown in FIG. 1, the polarization converter 414 is disposed
between the second lens array 413 and the superposing lens 415. The
polarization converter 414 aligns polarization directions of the
plurality of partial light beams divided by the first lens array 412.

[0067]As shown in FIG. 4, the lengthwise directions of the polarization
separating layers 4141 and the reflection layers 4142 are defined as a
first direction (a vertical direction indicated by arrow C in FIG. 3),
the first direction being in a plane orthogonal to the illumination
optical axis A. The polarization separation layers 4141 and the
reflection layers 4142 are alternately arranged in a second direction
(which is a horizontal direction indicated by arrow B in FIGS. 2 and 4),
the second direction being orthogonal to the illumination optical axis A
and the first direction.

[0068]The partial light beams divided by the first lens array 412 are
incident on the polarization separating layers 4141 through a light
incident surface 414A at positions corresponding to the polarization
separating layers 4141. In the polarization converter 414, the width of
the light incident surface 414A in the first direction is substantially
the same as the width of the polarization separating layers 4141 in the
first direction (the width in the lengthwise direction of the
polarization separating layers 4141). The width of the light incident
surface 414A in the second direction is substantially the same as the
width of the polarization separating layers 4141 in the second direction.

[0069]The polarization separating layer 4141 separates random polarized
light beams into two types of liner polarized light beams. The
polarization separating layer 4141 is a dielectric multi-layer film
capable of transmitting one polarized light beam out of the incident
light beams and reflecting the other polarized light beam.

[0070]The reflection layer 4142, which is a reflection film made of a
single metal or an alloy, reflects the polarized light beam reflected by
the polarization separating layer 4141 into the direction same as the
polarized light beam having passed through the polarization separating
layer 4141 toward the light beam emitting-side of the polarization
converter 414.

[0071]The glass member 4143 transmits the light beam therethrough. The
glass member 4143 is formed by machining a white glass sheet or the like
in the first exemplary embodiment.

[0072]The phase layers 4144 are provided on the light beam emitting-side
of the glass members 4143. The phase layer 4144 rotates the polarization
direction of the light beam irradiated from the glass member 4143 by 90
degrees such that the rotated polarization direction aligns with the
polarization direction of the other linear polarized light beam.

[0073]More specifically, the phase layer 4144 is affixed on the light beam
emitting-side surface of the glass member 4143 at a position where the
linear polarized light beam having passed through the polarization
separating layer 4141 is irradiated. The phase layer 4144 rotates by 90
degrees the polarization direction of the linear polarized light beam
having passed through the polarization separating layer 4141.

[0074]Note that the phase layer 4144 may be affixed on the light beam
emitting-side surface of the glass member 4143 at a position where the
linear polarized light beam reflected by the reflection layer 4142 is
irradiated such that the phase layer 4144 can rotate by 90 degrees the
polarization direction of the linear polarized light beam reflected by
the reflection layer 4142.

[0075]The light shield plates 4145 are disposed on the light incident side
of the glass members 4143. The light shield layers 4145 are made of
stainless steel or an aluminum alloy and disposed at positions
corresponding to the reflection layers 4142. Accordingly, the partial
light beams irradiated from the first and second lens arrays 412, 413 are
not directly incident on the reflection layers 4142 of the polarization
converter 414.

[0076]Specifically, the partial light beams irradiated from the first and
second lens arrays 412, 413 are incident only on the polarization
separating layers 4141 and unnecessary light beams are shielded by the
light shield plates 4145 so as not to be incident on the reflection
layers 4142. Hence, most of the partial light beams irradiated from the
second lens array 413 are incident on the light incident surface 414A on
the light incident side of the glass members 4143 at positions not
covered by the light shield plates 4145 and then on the polarization
separating layers 4141 through the glass members 4143.

[0077]Next described with reference to FIG. 4 will be how the polarization
separating layer 4141 of the polarization converter 414 transmits a P
polarized light beam and reflects an S polarized light beam.

[0078]The partial light beam irradiated from the second lens 4131 of the
second lens array 413 passes between the adjacent light shield plates
4145 to be incident on the light incident surface 414A of the
polarization converter 414 and then on the polarization separating layer
4141 through the glass member 4143. The polarization separating layer
4141 transmits the P polarized light beam in the partial light beams and
reflects the S polarized light beam toward the reflection layer 4142 by
converting the optical path of the S polarized light beam by 90 degrees.

[0079]The S polarized light beam incident on the reflection layer 4142 is
reflected by the reflection layer 4142 such that the optical path is
converted by 90 degrees toward the light beam emitting-side, so that the
S polarized light beam travels in the substantially same direction of the
illumination optical axis A.

[0080]The P polarized light beam having passed the polarization separating
layer 4141 is incident on the phase layer 4144. The polarization
direction is rotated by 90 degrees by the phase layer 4144, so that the P
polarized light beam is irradiated as the S polarized light beam. Thus,
only substantially one type of light beam (i.e. the S polarized light
beam) is irradiated from the polarization converter 414.

[0081]Note that in the case of the projector using the liquid crystal
panel that modulates the linear polarized light beam, only uniform type
of linear polarized light beams can be used, so that it is impossible to
utilize substantially half of the light beams irradiated from the light
source device 411 that emits random polarized light beams. Accordingly,
the first exemplary embodiment employs the polarization converter 414
such that the light beams irradiated from the light source device 411 can
be converted into substantially one type of liner polarized light beams,
thereby enhancing light use efficiency of the electrooptical device 44.

[0082]Thus, the partial light beams converted into substantially one type
of linear polarized light beams by the polarization converter 414 are
superposed by the superposing lens 415 on the image formation area (an
light modulating surface) of the later-described liquid crystal panel 441
of the electrooptical device 44.

[0083]As shown in FIG. 1, the color-separating optical device 42 is a
color-separating optical system including two dichroic mirrors 421, 422
and a reflection mirror 423. The dichroic mirrors 421, 422 separate the
plurality of partial light beams irradiated from the illumination optical
device 41 into three color light beams of red (R), green (G) and blue
(B).

[0085]The dichroic mirror 421 of the color-separating optical device 42
transmits a red light component and a green light component of the light
beam irradiated by the illumination optical device 41. The dichroic
mirror 421 reflects a blue light component. The blue light beam reflected
by the dichroic mirror 421 is also reflected by the reflection mirror 423
to travel through a field lens 419 to reach a blue liquid crystal panel
441B. The field lens 419 converts the partial light beams irradiated by
the second lens array 413 into light beams parallel to the central axis
(a main optical axis) of the field lens 419. The field lenses 419
provided on the light incident sides of a green liquid crystal panel 441G
and the red liquid crystal panel 441R work in the same manner. The green
light beam out of the red and green light beams having passed through the
dichroic mirror 421 is reflected by the dichroic mirror 422 to travel
through the field lens 419 to reach the green liquid crystal panel 441G.
The red light beam passes through the dichroic mirror 422, the relay
optical device 43 and the field lens 419 to reach the red liquid crystal
panel 441R. Note that the relay optical device 43 is employed for the red
light beam to prevent a reduction in the light use efficiency caused by
light dispersion or the like, since the optical path of the red light
beam is longer than those of the light beams of the other colors. In
other words, the relay optical device 43 is employed such that the
partial light beams incident on the incident-side lens 431 can reach the
field lens 419. Note that the relay optical device 43 is adapted to
transmit the red light beam, but the arrangement is not limited thereto.
The relay optical device 43 may transmit, for example, the blue light
beam.

[0087]As shown in FIG. 1, the electrooptical device 44 includes the liquid
crystal panels 441 as the optical modulators (the red, green and blue
liquid crystal panels 441R, 441G and 441B), three incident-side
polarization plates 442 respectively disposed on the light incident sides
of the liquid crystal panels 441, three angle of view compensating plates
443 respectively disposed on the light beam emitting-sides of the liquid
crystal panels 441, three emitting-side polarization plates 444
respectively disposed on the light beam emitting-sides of the angle of
view compensating plates 443 and a cross dichroic prism 445 as the
color-combining optical device.

[0088]Incident on the incident-side polarization plates 442 are the color
light beams aligned in the substantially uniform polarization direction
by the polarization converter 414. The incident-side polarization plate
442 transmits the polarized light beams out of the incident light beams,
the polarized light beams being in the substantially same direction as
the polarization direction of the light beams aligned by the polarization
converter 414. The incident-side polarization plate 442 absorbs the other
light beams. The incident-side polarization plate 442 may be a
light-transmissive substrate with a polarization layer affixed thereon,
the substrate being of sapphire glass, crystal or the like.

[0089]Although not shown in the figures, the liquid crystal panel 441 as
the optical modulator is formed of a pair of light-transmissive glass
substrates with a liquid crystal element (an electrooptic material)
sealed therebetween. The orientation of the liquid crystal element in the
liquid crystal panel 441 is controlled by a drive signal from the control
device, so that the polarization direction of the polarized light beam
irradiated from the incident-side polarization plate 442 is modulated.

[0090]The angle of view compensating plate 443 having a film-like shape
compensates a phase difference between an ordinary light and an
extraordinary light caused by a birefringence on the liquid crystal panel
441, the birefringence being generated when the light beam is obliquely
incident on the liquid crystal panel 441 (i.e. when the light beam is
incident obliquely relative to the normal line of the panel surface). The
angle of view compensating plate 443 is a negatively uniaxial anisotropic
body of which optical axis is oriented in a predetermined direction in
the film plane and inclined in an out-plane direction of the film plane
with a predetermined angle.

[0091]The angle of view compensating plate 443 may be formed by providing
a discotic (disc like shaped) compound layer via an orientation layer on
a light-transmissive support body made of for example triacetate (TAC).
The angle of view compensating plate 443 may be a WV film available from
FUJIFILM Corporation.

[0092]Out of the light beams irradiated from the liquid crystal panel 441
passed through the angle of view compensating plate 443, the
emitting-side polarization plate 444 transmits the light beam having the
polarization direction orthogonal to a transmissive axis of the light
beam on the incident-side polarization plate 442 and absorbs the other
light beams.

[0093]The cross dichroic prism 445 combines the modulated light that is
irradiated from the emitting-side polarization plate 444 and modulated
for each color to form an optical image (a color image). The cross
dichroic prism 445 is square in plan view and is formed of four
right-angle prisms attached together, two dielectric multi-layer films
being formed on the boundaries of the right-angle prisms. The dielectric
multi-layer films transmit the color light beam having passed through the
emitting-side polarization plate 444 disposed on the opposite side of the
projection lens 3 (on the green color side) and reflect the color light
beams having passed through the other two emitting-side polarization
plates 444 (the red and blue color sides). Thus, the color light beams
modulated by the incident-side polarization plates 442, the liquid
crystal panels 441, the angle of view compensating plates 443 and the
emitting-side polarization plates 444 are combined into a color image.

[0094]3 Focal Position of First Lens 4121

[0095]As described above, the plurality of first lenses 4121 of the first
lens array 412 divide the light beam irradiated from the light source
device 411 into the plurality of partial light beams and irradiate the
partial light beams to the corresponding second lenses 4131 of the second
lens array 413. Toric lenses are employed as the first lenses 4121, so
that a plurality of focal positions can be set in the second and first
directions, the second direction being the horizontal direction in which
the polarization separating layers 4141 and the reflection layers 4142 of
the polarization converter 414 are aligned (arrow B in FIG. 2) and the
first direction being the vertical direction (the lengthwise direction)
of the polarization separating layers 4141 and the reflection layers 4142
of the polarization converter 414 (arrow C in FIG. 3).

[0096]By employing the toric lens as the first lens 4121, it is possible
not only to flexibly set the focal positions in the first and second
directions but also to easily arrange the first lenses 4121.

[0097]As shown in FIG. 2, the focal position in the second direction of
the first lens 4121 is set in the vicinity of the polarization converter
414 in the optical axis direction of the light beam irradiated from the
first lens 4121. Specifically, the focal position in the second direction
is set substantially at the center of the polarization separating layer
4141 of the polarization converter 414 on which the light beam is
incident via the corresponding second lens 4131.

[0098]As shown in FIG. 3, the focal position in the first direction of the
first lens 4121 is set in the vicinity of the second lens array 413 in
the optical axis direction of the light beam irradiated from the first
lens 4121. Specifically, the focal position in the first direction is set
substantially at the center of the corresponding second lens 4131.

[0099]4 Optical Path of Light Irradiated from Light Source Device 416

[0100]4-1 Optical Path of First Comparison to First Exemplary Embodiment

[0101]A first comparison will be described, in which a focal position of a
first lens 412A1 of a first lens array 412A is set in the vicinity of the
second lens array 413.

[0102]FIG. 5 is a schematic illustration showing optical paths of light
beams irradiated from the light source lamp 416 of the optical unit 4,
the optical unit 4 including the first lens 412A1 of the first
comparison. FIG. 6 is an illustration showing a portion of FIG. 5 in an
enlarged manner. Note that the first lens array 412A is different from
the first lens array 412 of the first exemplary embodiment in that the
focal position in the second direction of the first lens 412A1 of the
first lens array 412A is set in the vicinity of the second lens array
413. However, the first lens array 412A is the same as the first lens
array 412 in that the first lens array 412A has the plurality of first
lenses 412A1.

[0103]Note that FIGS. 5 and 6 contain no aberration in the illumination
optical axis A direction for easy description. FIGS. 5 and 6 focus on one
first lens 412A1 out of the plurality of first lenses 412A1 of the first
lens array 412A and show a corresponding second lens 4131 and a
corresponding portion of the polarization converter 414 both
corresponding to the first lenses 412A1.

[0104]As shown in FIGS. 5 and 6, when the center O of the light emitting
portion D of the light source lamp 416 is positioned substantially at the
middle of the electrodes, incident on the first lens 412A1 of the first
lens array 412A via the reflector 417 and the collimating lens 418 are
the light (shown in the solid lines) irradiated from the center O of the
light emitting portion D; the light (shown in the broken lines)
irradiated from a position O1 on an outer side of the center O of the
light emitting portion D, the position O1 being displaced in the second
direction (arrow B in FIGS. 5 and 6) from the center O of the light
emitting portion D toward the outer side of the center O; and the light
(shown in the dashed lines) irradiated from a position O2 which is an
outermost position on the outer side in the second direction of the light
emitting portion D. The light irradiated from the light emitting portion
D passes through the first lens 412A1 to be divided into partial light
beams which further travel from the first lens 412A1 to the corresponding
second lens 4131 of the second lens array 413. However, the more the
light irradiation position is displaced from the center O of the light
emitting portion D, the more the light incident position of the partial
light beams on the second lens 4131 is displaced in the opposite
direction of the displaced direction of the light irradiation position of
the light from which the partial light beams are generated.

[0105]For example, the partial light beams generated from the light
irradiated from the outermost position O2 displaced from the center O of
the light emitting portion D in the second direction toward the outer
side (shown in the dashed lines) are incident on the corresponding second
lens 4131 at an incident position near one end of the corresponding
second lens 4131 in the direction which extends from the light
irradiation position to the center O of the light emitting portion D.
Each light incident on the second lens 4131 is then incident on the light
incident surface 414A of the polarization converter 414. Since the focal
position in the second direction of the first lens 4121 is set in the
vicinity of the second lens array 413, the light beam irradiated from the
second lens 4131 travels in an expanding manner to be incident on the
light incident surface 414A in a large illumination region.

[0106]However, when the center O of the light emitting portion D is
positioned substantially at the middle of the electrodes 4164, 4165,
substantially all the light of the partial light beams generated from the
light irradiated from the center of the light emitting portion D and
substantially all the light of the partial light beams generated from the
light irradiated from the outermost position in the second direction of
the light emitting portion D are both incident on the light incident
surface 414A of the polarization converter 414. The same applies to all
first lenses 412A1 and the partial light beams from the first lenses
412A1 are superposed on the image formation area of the liquid crystal
panel 441. Thus, the image formation area of the liquid crystal panel 441
is illuminated with uniform luminance.

[0107]Next described will be the first comparison in which the light
emitting portion D of the light source lamp 416 is moved in the second
direction (arrow B).

[0108]When the light emitting portion D of the light source lamp 416 is
moved in the second direction (arrow B) substantially from the middle of
the electrodes 4164, 4165, the partial light beams generated by the first
lens 412A1 to be incident on the corresponding second lens 4131 are
generally incident on the second lens 4131 with the displacement in the
opposite direction of the movement direction of the light emitting
portion D as described above and then incident on the light incident
surface 414A of the polarization converter 414 with a similar
displacement toward the opposite direction of the movement direction.

[0109]For example, when the light emitting portion D is moved upward in
FIG. 5 (one side of arrow B in FIG. 5), the light beam irradiated from
the first lens 412A1 is incident on the corresponding second lens 4131 at
a position displaced toward the end on the lower side in FIG. 5 (the
other side of arrow B in FIG. 5) and then incident on the light incident
surface 414A also at a position displaced toward the end on the lower
side.

[0110]Accordingly, the more the light emitting portion D is moved in the
second direction, the more difficult for the partial light beams
irradiated from the first lens 412A1 to be incident on the light incident
surface 414A as the light irradiation position of the light from which
the partial light beams are generated becomes farther from the center O
of the light emitting portion D in the movement direction of the light
emitting portion D.

[0111]More specifically, when the position of the light emitting portion D
is moved upward in FIG. 5, the partial light beams generated from the
light irradiated form the moved light emitting portion D are incident on
the corresponding second lens 4131 with a larger displacement in the
opposite direction of the movement direction of the light emitting
portion D, compared with the case in which the center O of the light
emitting portion D is substantially at the middle of the electrodes. The
same applies to the light incident on the light incident surface 414A of
the polarization converter 414. As shown in FIGS. 5 and 6, the focal
position of the first lens 412A1 of the first comparison is set in the
vicinity of the second lens 4131, so that the partial light beams
irradiated form the first lens 412A1 are converged in the vicinity of the
second lens 4131 and expand in the vicinity of the light incident surface
414A of the polarization converter 414 to be incident thereon. Hence, the
illumination region of the partial light beams incident on the light
incident surface 414A of the polarization converter 414 becomes large.

[0112]Accordingly, when the light emitting portion D is moved in the
second direction by a predetermined distance, substantially all the
partial light beams generated from the light irradiated from the center O
of the light emitting portion D out of the light irradiated from the
light emitting portion D are incident on the light incident surface 414A
of the polarization converter 414. However, in the case of the partial
light beams generated from the light irradiated from an end position in
the movement direction of the light emitting portion D, the light of the
partial light beams is partially out of the light incident surface 414A
of the polarization converter 414 at an end on the opposite side of the
end position in the movement direction of the light emitting portion D to
be incident on the light shield plate 4145.

[0113]When the light emitting portion D is further moved in the second
direction by a larger distance than the predetermined distance, not only
the light of the partial light beams generated from the light irradiated
from the end position in the movement direction of the light emitting
portion D but also the light of the partial light beams generated from
the light irradiated from a position closer to the center O compared to
the end position in the movement direction are partially out of the light
incident surface 414A of the polarization converter 414 to be incident on
the light shield plate 4145.

[0114]That is, when the light emitting portion D is moved in the second
direction by a certain distance, the partial light beams are partially
out of the light incident surface 414A of the polarization converter 414
to be incident on the light shield plate 4145 regardless of the
irradiation position of the light in the light emitting portion D. In the
light emitting portion D moved in the second direction by a certain
distance, when comparing the ratios of the light incident on the light
shield plate 4145 to the total light of the partial light beams between
the partial light beams generated from the light irradiated from the
center O of the light emitting portion D and the partial light beams
generated from the light irradiated from a position displaced in the
movement direction from the center O of the light emitting portion D, the
latter case represents a higher ratio. That is to say, the partial light
beams generated from the light irradiated from a position apart from the
light emitting portion D are incident on the light shield plate 4145 at a
higher rate.

[0116]FIG. 7 shows a relation between the movement amount in the second
direction of the light emitting portion D and luminance distribution in
the first comparison. Specifically, in FIG. 7, the solid line shows the
luminance distribution on the liquid crystal panel 441 when the center O
of the light emitting portion D is substantially at the middle of the
electrodes. The broken line shows the luminance distribution on the
liquid crystal panel 441 when the center O of the light emitting portion
D is moved in the second direction substantially from the middle of the
electrodes. The dashed line shows the luminance distribution on the
liquid crystal panel 441 when the center of the light emitting portion D
is moved in the second direction substantially from the middle of the
electrodes by a longer distance than the case of the broken line.

[0117]As described above, when the light emitting portion D is moved in
the second direction by a certain distance substantially from the middle
of the electrodes 4164, 4165, the partial light beams generated from the
light irradiated from different positions in the light emitting portion D
are partially out of the light incident surface 414A of the polarization
converter 414 and incident on the light shield plate 4145. In other
words, when the center O of the light emitting portion D is moved in the
second direction by a certain distance, the partial light beams generated
from the light irradiated from the light emitting portion D illuminate
the image formation area of the liquid crystal panel 441 with portion
thereof reduced, the reduced portion being incident on the light shield
plate 4145 of the polarization converter 414, although the ratios of the
light to be incident on the light incident surface 414A to the light to
be incident on the light shield plate 4145 depend on the irradiation
position of the light in the light emitting portion D from which the
partial light beams are generated.

[0118]For example, the partial light beams generated from the light
irradiated from the center O of the light emitting portion D illuminate
the image formation area of the liquid crystal panel 441 with portion
thereof reduced on one end side by the light shield plate 4145 and the
partial light beams generated from the light irradiated from a position
displaced in the movement direction of the light emitting portion D from
the center O of the light emitting portion D illuminate the image
formation area of the liquid crystal panel 441 with portion thereof
reduced on the one end side by the light shield plate 4145.

[0119]Thus, even if the partial light beams with portion thereof reduced
by the light shield plate 4145 on the one end side are superposed on the
image formation area of the liquid crystal panel 441, it is impossible to
illuminate the image formation area with uniform luminance. Accordingly,
as shown in the broken and dashed lines in FIG. 7, one end side of the
image formation area is illuminated with higher luminance than the other
end side.

[0120]When thus superposed light beams are modulated by the liquid crystal
panels 441 to form an image in accordance with the color light beams, the
image will have higher brightness on one end side in the second direction
(the horizontal direction) than on the other end side. Note that the
light beams superposed on the image formation areas of the liquid crystal
panels 441 have been reflected by the mirrors of the color-separating
optical device 42 and the relay optical device 43. In addition, the red
and blue light beams have been reflected by the cross dichroic prism 445
that combine the color light beams as images. Hence, in the optical image
formed by the cross dichroic prism 445 by combining the color light
beams, the color images of red, green and blue have the higher brightness
on different sides, thereby causing color unevenness.

[0121]4-3 Second Comparison to First Exemplary Embodiment

[0122]Next described will be a second comparison in which the light
emitting portion D of the light source lamp 416 is moved in the first
direction.

[0123]In the second comparison, the focal position in the first direction
(the vertical direction) of the first lens of the first lens array is set
in the vicinity of the light incident surface 414A of the corresponding
polarization converter 414.

[0124]In the second comparison, when the center O of the light emitting
portion D is positioned substantially at the middle of the electrodes
4164, 4165, the light irradiated from the center O of the light emitting
portion D is incident substantially on the center of the corresponding
second lens 4131 via the first lens as described above. The light
irradiated from an outer position in the first direction of the light
emitting portion D is incident via the first lens on the corresponding
second lens 4131 on the end displaced in the opposite direction of the
movement direction in which the light irradiation position is moved from
the center O of the light emitting portion D. When the focal position in
the first direction of the first lens is set in the vicinity of the light
incident surface 414A of the polarization converter 414, the light
irradiated from the first lens is incident on the second lens 4131 in a
large illumination region before light convergence on the focal position.
However, when the center O of the light emitting portion D is positioned
substantially at the middle of the electrodes 4164, 4165, substantially
all the light of the partial light beams generated from the light
irradiated from the center in the first direction of the light emitting
portion D and substantially all the light of the partial light beams
generated from the light irradiated from the outermost position in the
first direction are both incident on the second lens 4131. The same
applies to all first lenses 412A1 and the partial light beams are
superposed on the image formation areas of the liquid crystal panels 441.
Accordingly, the image formation area of the liquid crystal panel 441 is
illuminated with uniform luminance.

[0125]However, although not shown in the figures, also in the second
comparison, when the position of the light emitting portion D of the
light source lamp 416 is moved in the first direction (the vertical
direction) substantially from the middle of the electrodes 4164, 4165,
luminance unevenness occurs in the image formation area of the liquid
crystal panel 441 in a similar manner to the first comparison, thereby
causing color unevenness in the formed optical image.

[0126]Specifically, when the light emitting portion D of the light source
lamp 416 is moved in the first direction, the partial light beams to be
incident on the second lens 4131 via the first lens are generally
incident on the corresponding second lens 4131 with displacement toward
the direction opposite to the movement direction of the light emitting
portion D. Hence, the more the light emitting portion D is moved in the
first direction such that the light irradiation position of the light
becomes farther from the center O of the light emitting portion D in the
movement direction of the light emitting portion D, the more difficult
for the partial light beam irradiated from the first lens to be incident
on the second lens 4131.

[0127]That is, since the focal position in the first direction of the
first lens in the second comparison is set in the vicinity of the light
incident surface 414A of the corresponding polarization converter 414,
the partial light beams irradiated from the first lens enter the second
lens 4131 while converging in the vicinity of the second lens 4131 and
converge at maximum in the vicinity of the light incident surface 414A of
the polarization converter 414.

[0128]Hence, the illumination region is large when the partial light beams
are incident on the second lens 4131. When the light emitting portion D
is moved in the first direction by a predetermined distance,
substantially all the partial light beams generated from the light
irradiated from the center O of the light emitting portion D are incident
on the corresponding second lens 4131. In the case of the partial light
beams generated from the light irradiated from the end position in the
movement direction of the light emitting portion D in the light emitting
portion D, the light of the partial light beams on the end displaced in
the direction opposite to the movement direction of the light emitting
portion D is partially out of the corresponding second lens 4131 and
incident on another second lens 4131 which is next to the corresponding
second lens 4131 in the first direction.

[0129]When the light emitting portion D is moved in the first direction by
a larger distance than the predetermined distance, not only the light of
the partial light beams generated from the light irradiated from the end
position in the movement direction of the light emitting portion D but
also the light of the partial light beams generated from the light
irradiated from a position closer to the center O of the light emitting
portion D compared to the end in the movement direction are partially out
of the second lens 4131 to be incident on the other second lens 4131.

[0130]That is, when the light emitting portion D is moved in the first
direction by a certain distance, the light of the partial light beams
generated from the light irradiated from different positions of the light
emitting portion D is always partially incident on the other second lens
4131 next to the corresponding second lens 4131. In the light emitting
portion D at a position displaced in the first direction, when comparing
the ratios of the light to be incident on the second lens 4131 between
the partial light beams generated from the light irradiated from the
center O of the light emitting portion D and the partial light beams
generated from the light irradiated from positions displaced in the
movement direction from the center O of the light emitting portion D, the
latter case represents a larger ratio, in which the partial light beams
are generated from the light irradiated from a position displaced from
the light emitting portion D.

[0131]The partial light beams incident on the next second lens 4131 are
not superposed on the image formation area of the liquid crystal panel
441. That is, similarly to the above-described first comparison, even if
the partially-reduced partial light beams are superposed on the image
formation area of the liquid crystal panel 441 (the partial reduction
being caused by that the light on one side of the light emitting portion
D is not incident on the corresponding second lens 4131), it is
impossible to illuminate the image formation area with uniform luminance.
Accordingly, the image formation area is illuminated with higher
luminance on the other end side than on the one end side, thereby causing
luminance unevenness in the image formation area. Further, if such light
beams are modulated during the transmission through the image formation
area and the modulated light beams are combined by the cross dichroic
prism 445, the formed optical image will contain color unevenness as
described above,

[0132]4-4 Optical Path of First Exemplary Embodiment

[0133]Next described will be the first lens 4121 of the first exemplary
embodiment, of which focal position in the second direction (the
horizontal direction, arrow B in FIG. 8) is set in the vicinity of the
corresponding polarization separating layer 4141 and focal position in
the first direction (the vertical direction, arrow C in FIG. 3) is set in
the vicinity of the corresponding second lens 4131.

[0134]FIG. 8 is an illustration showing an optical path of a light beam
irradiated from the light source lamp 416 of the optical unit 4 of the
first exemplary embodiment, the optical unit 4 including the first lens
4121 of which focal position in the second direction is set in the
vicinity of the polarization converter 414. FIG. 9 is an illustration
showing a portion of FIG. 8 in an enlarged manner. FIGS. 8 and 9 include
no aberration in the illumination optical axis A direction for easy
description. FIGS. 8 and 9 focus on one first lens 4121 out of the
plurality of first lenses 4121 of the first lens array 412 and show a
corresponding second lens 4131 and a corresponding portion of the
polarization converter 414 both corresponding to the first lenses 4121.

[0135]However, in the first lens 4121 of the first exemplary embodiment,
when the center O of the light emitting portion D is positioned
substantially at the middle of the electrodes 4164, 4165, substantially
all the light of the partial light beams generated from the light
irradiated from the center in the second direction of the light emitting
portion D and substantially all the light of the partial light beams
generated from the light irradiated from the outermost position in the
second direction are both incident on the light incident surface 414A of
the polarization converter 414. The same applies to all first lenses 4121
of the first lens array 412. The image formation area of the liquid
crystal panel 441 is illuminated with uniform luminance with the partial
light beams irradiated from the first lens 4121.

[0136]Next described will be the case in which the light emitting portion
D of the light source lamp 416 is moved in the second direction (the
horizontal direction, arrow B in FIGS. 8 and 9) substantially from the
middle of the electrodes 4164, 4165.

[0137]When the light emitting portion D of the light source lamp 416 is
moved in the second direction (the horizontal direction), the partial
light beams travel through the first lens 4121 and enter the
corresponding second lens 4131 with the above-described displacement in
the opposite direction of the movement of the light emitting portion D
and then enter the light incident surface 414A of the polarization
converter 414 with the same displacement in the opposite direction.

[0138]In contrast to the above-described first comparison, the focal
position in the second direction of the first lenses 4121 of the first
exemplary embodiment is set in the vicinity of the polarization converter
414 on the optical axes of the partial light beams (the central axes of
the partial light beams) irradiated from the first lenses 4121, so that
the partial light beams irradiated from the light source lamp 416 via the
first lenses 4121 are most highly converged in the vicinity of the light
incident surface 414A of the polarization converter 414 as shown in FIGS.
8 and 9, thereby reducing the size of the illumination region of the
partial light beams on the light incident surface 414A of the
polarization converter 414.

[0139]Hence, in the polarization converter 414, the illumination region of
the incident partial light beams is small, so that when the light
emitting portion D is moved in the second direction by a predetermined
distance, substantially all the light of the partial light beams
generated from the light irradiated from the center O of the light
emitting portion D is incident on the light incident surface 414A of the
polarization converter 414. In contrast, substantially all the light of
the partial light beams generated from the light irradiated from a
position in the vicinity of the end in the movement direction of the
light emitting portion D is out of the light incident surface 414A of the
polarization converter 414 and incident on the light shield plate 4145.

[0140]When the light emitting portion D is moved in the second direction
by a larger distance than the predetermined distance, not only
substantially all the light of the partial light beams generated from the
light irradiated from end positions in the movement direction of the
light emitting portion D but also substantially all the light of the
partial light beams generated from the light irradiated from a position
closer to the center O compared to the end in the movement direction are
out of the light incident surface 414A of the polarization converter 414
and incident on the light shield plate 4145. That is, when the light
emitting portion D is moved in the second direction by a certain
distance, substantially all the light of some partial light beams out of
the partial light beams generated from the light irradiated from
different positions of the light emitting portion D is out of the light
incident surface 414A of the polarization converter 414 and incident on
the light shield plate 4145. The more the light emitting portion D is
moved in the second direction, the larger an area in the light emitting
portion D becomes, from the area the light of the partial light beams to
be out of the light incident surface 414A of the polarization converter
414 and incident on the light shield plate 4145 being irradiated.

[0141]Hence, the first exemplary embodiment is different from the first
comparison in which each light of the partial light beams generated from
the light irradiated from different positions of the light emitting
portion D is partially out of the light incident surface 414A of the
polarization converter 414. The first exemplary embodiment differs from
the first compassion in that substantially all the light of some partial
light beams out of the partial light beams generated from the light
irradiated from different positions in the light emitting portion D is
out of the light incident surface 414A of the polarization converter 414
and incident on the light shield plate 4145.

[0142]Note that the focal position in the second direction of the first
lenses 4121 is set in the vicinity of the polarization converter 414 on
the optical axes of the partial light beams irradiated from the first
lenses 4121. Since the partial light beams to be incident on the second
lens 4131 are just before the maximum convergence, the illumination
region of the partial light beams is large. However, the width in the
second direction of the second lens 4131 is larger than the width in the
second direction of the light incident surface 414A of the polarization
converter 414. Accordingly, even when the light emitting portion D is
moved in the second direction by a certain distance, it will not happen
that the light of the partial light beams is partially out of the
corresponding second lens 4131 before being shielded by the light shield
plate 4145 of the polarization converter 414.

[0144]FIG. 10 shows a relation between a movement amount in the second
direction of the light emitting portion D and luminance distribution on
the liquid crystal panel 441 of the first exemplary embodiment.
Specifically, in FIG. 10, the solid line shows the luminance distribution
on the liquid crystal panel 441 when the light emitting portion D is
substantially at the middle of the electrodes 4164, 4165. The broken line
shows the luminance distribution on the liquid crystal panel 441 when the
light emitting portion D is moved in the second direction substantially
from the middle of the electrodes 4164, 4165. The dashed line shows the
luminance distribution on the liquid crystal panel 441 when the light
emitting portion D is moved in the second direction from the position of
the light emitting portion D of the broken line.

[0145]As described above, when the light emitting portion D is moved in
the second direction by a certain distance, substantially all the light
of some partial light beams of the partial light beams generated from the
light irradiated from each position of the light emitting portion D is
out of the light incident surface 414A of the polarization converter 414
and is incident on the light shield plate 4145.

[0146]That is, in the case of the partial light beams generated from the
light irradiated from the center O of the light emitting portion D,
substantially all the light illuminates the image formation area of the
liquid crystal panel 441. In contrast, in the case of the partial light
beams generated from the light irradiated from a position displaced in
the movement direction of the light emitting portion D to be apart from
the center O of the light emitting portion D, substantially all the light
is shielded by the light shield plate 4145 so as not to illuminate the
image formation area of the liquid crystal panel 441.

[0147]Thus, in the first exemplary embodiment when the light emitting
portion D is moved in the second direction substantially from the middle
of the electrodes 4164, 4165, although an area in the light emitting
portion D from which the light to be divided into the partial light beams
superposed on the image formation area of the liquid crystal panel 441 is
small, substantially all the light of the partial light beams generated
from the light irradiated from the other area in the light emitting
portion D is superposed on the image formation area of the liquid crystal
panel 441. Accordingly, the luminance on the image formation area of the
liquid crystal panel 441 is lowered, but the luminance can be uniform on
the image formation area.

[0148]As stated above, the arrangement of the first exemplary embodiment
reduces a difference in the luminance between one end and the other end
in the second direction when the partial light beams generated from each
light irradiated from the light emitting portion D are superposed on the
image formation area of the liquid crystal panel 441, thereby reducing
luminance unevenness on the image formation area.

[0149]Even when the light emitting portion D of the light source lamp 416
is moved in the second direction, substantially uniformly illuminating
the image formation area of the liquid crystal panel 441 reduces color
unevenness of the optical image formed by combing the color light beams
of red (R), green (G) and blue (B) having passed through the image
formation areas by the cross dichroic prism 445.

[0150]On the other hand, the focal position in the first direction (the
vertical direction) of the first lens 4121 of the first lens array 412 is
set in the vicinity of the second lens array 413 on the optical axis of
the light beam irradiated from the first lens 4121. Hence, even when the
light emitting portion D of the light source lamp 416 is moved in the
first direction (the vertical direction), the luminance unevenness on the
image formation area of the liquid crystal panel 441 can be reduced,
thereby reducing the color unevenness in the formed image.

[0151]The more detailed description will be given below.

[0152]When the light emitting portion D of the light source lamp 416 is
moved in the first direction substantially from the middle of the
electrodes 4164, 4165, the partial light beam to be incident on the
corresponding second lens 4131 via the first lens 4121 is incident on the
corresponding second lens 4131 with displacement toward the direction
opposite to the movement direction of the light emitting portion D.

[0153]Accordingly, the more the light emitting portion D is moved in the
first direction such that the light irradiation position becomes farther
from the center O of the light emitting portion D in the movement
direction of the light emitting portion D, the more difficult for the
partial light beam irradiated from the first lens 4121 to be incident on
the second lens 4131.

[0154]In the first exemplary embodiment, since the focal position in the
first direction (the vertical direction) of the first lens 4121 is set in
the vicinity of the second lens 4131 on the optical axis of the partial
light beam irradiated from the first lens 4121, the partial light beam
irradiated from the first lens 4121 is incident on the corresponding
second lens 4131 in a small illumination region.

[0155]Hence, when the light emitting portion D is moved in the first
direction by a predetermined distance, substantially all the light of the
partial light beams generated from the light irradiated from the center O
of the light emitting portion D is incident on the corresponding second
lens 4131. On the other hand, substantially all the light of the partial
light beams generated from the light irradiated from an end position of
the light emitting portion D in the movement direction is out of the
corresponding second lens 4131 and incident on the other second lens 4131
next to the corresponding second lens 4131 in the first direction.

[0156]When the light emitting portion D is moved in the first direction by
a larger distance more than the predetermined distance, not only
substantially all the light of the partial light beams generated from the
light irradiated from the end position in the movement direction of the
light emitting portion D in the light emitting portion D, but also
substantially all the light of the partial light beams generated from the
light irradiated from a position more closer to the center O than to the
end in the movement direction is incident on the other second lens 4131
next to the corresponding second lens 4131 in the first direction.

[0157]That is, when the light emitting portion D is moved in the first
direction by a certain distance, regardless of the irradiation position
in the light emitting portion D, substantially all the light of some
partial light beams from a position in the light emitting portion D is
out of the corresponding second lens 4131 and incident on the other
second lens 4131 next to the corresponding second lens 4131 in the first
direction. The more the light emitting portion D is moved in the first
direction, the larger the region becomes from which the light to be
divided into the partial light beams to be out of the corresponding
second lens 4131 and incident on the other second lens 4131 that is next
to the corresponding second lens 4131 in the first direction is
irradiated.

[0158]Hence, in the first exemplary embodiment, similarly to the
above-described second comparison, the light of each partial light beam
generated from the light irradiated from the different positions in the
light emitting portion D is partially out of the corresponding second
lens 4131 to be incident on the other second lens 4131 next to the
corresponding second lens in the first direction, but substantially all
the light of some partial light beams out of the total partial light
beams is out of the corresponding second lens 4131 and incident on the
other second lens 4131 next to the corresponding second lens 4131 in the
first direction.

[0159]Note that since the focal position in the first direction of the
first lens 4121 is set in the vicinity of the corresponding second lens
4131 on the optical axis of the partial light beam irradiated from the
first lens 4121, the partial light beam incident on the light incident
surface 414A of the polarization converter 414 gradually expands such
that the illumination region becomes larger. However, the width of the
light incident surface 414A of the polarization converter 414 in the
first direction is wider than that of the second lens 4131 in the first
direction. Accordingly, even when the light emitting portion D is moved
in the first direction by a certain distance, a case will not occur in
which the light of some partial light beams out of the partial light
beams is not incident on the light incident surface 414A of the
polarization converter 414 before the partial light beams enter the light
incident surface 414A of the polarization converter 414.

[0160]As described above, when the light emitting portion D is moved in
the first direction substantially from the middle of the electrodes 4164,
4165 by a certain distance, substantially all the light of some partial
light beams out of the partial light beams generated from the light
irradiated from different positions in the light emitting portion D is
out of the corresponding second lens 4131 and incident on the other
second lens 4131 next to the corresponding second lens 4131 in the first
direction. The light incident on the next second lens 4131 is not
superposed on the image formation area as stated above.

[0161]That is, in the case of the partial light beams generated from the
light irradiated from the center O of the light emitting portion D,
substantially all the light of the partial light beams illuminates the
image formation area of the liquid crystal panel 441. On the other hand,
in the case of the partial light beams generated from the light
irradiated from a position displaced in the movement direction of the
light emitting portion D to be apart from the center O of the light
emitting portion D, substantially all the light of the partial light
beams is incident on the other second lens 4131 next to the corresponding
second lens 4131 so as not to illuminate the image formation area of the
liquid crystal panel 441.

[0162]Thus, in the first exemplary embodiment when the light emitting
portion D is moved in the first direction, although an area from which
the light to be divided into the partial light beams superposed on the
image formation area of the liquid crystal panel 441 is small,
substantially all the light of the partial light beams generated from the
light irradiated from the other area in the light emitting portion D is
superposed on the image formation area of the liquid crystal panel 441.
Hence, the illumination intensity on the image formation area is lowered
as a whole, but the illumination intensity can be uniform on the image
formation area. Accordingly, luminance unevenness is reduced on the image
formation area of the liquid crystal panel 441.

[0163]Even when the light emitting portion D is moved in the first
direction, uniformly illuminating the image formation area of the liquid
crystal panel 441 reduces color unevenness of the optical image formed by
combing the color images of red (R), green (G) and blue (B) on the image
formation areas by the cross dichroic prism 445.

[0164]The projector of the first exemplary embodiment provides advantages
below.

[0165]The focal position in the second direction (the horizontal
direction) of the first lens 4121 of the first lens array 412 is set in
the vicinity of the polarization converter 414 on the optical axis of the
light beam irradiated from the first lens 4121.

[0166]Accordingly, when the light emitting portion D of the light source
lamp 416 is moved in the second direction, the light irradiation position
in the light emitting portion D determines whether the partial light
beams generated from the light passing through the first lens 4121 are
incident on the light incident surface 414A of the polarization converter
414. In other words, when the partial light beams generated from the
light irradiated from a certain position in the light emitting portion D
are incident on the light incident surface 414A, substantially all the
light of the partial light beams is not shielded by the light shield
plate 4145 but incident on the light incident surface 414A. On the other
hand, when the partial light beams generated from the light irradiated
from a certain position in the light emitting portion D are shielded by
the light shield plate 4145 so as not to be incident on the light
incident surface 414A, substantially all the light of the partial light
beams is shielded by the light shield plate 4145. Hence, most of the
partial light beams incident on the light incident surface 414A is not
partially reduced, superposing such partial light beams can illuminate
the image formation area of the liquid crystal panel 441 substantially
uniformly.

[0167]Hence, even when the light emitting portion D is moved in the second
direction substantially from the middle of the electrodes 4164, 4165,
luminance unevenness on the image formation area can be reduced.

[0168]The focal position in the first direction of the first lens 4121 is
set in the vicinity of the second lens 4131 on the optical axis of the
light beam irradiated from the first lens 4121.

[0169]Accordingly, when the light emitting portion D of the light source
lamp 416 is moved in the first direction, the light irradiation position
in the light emitting portion D determines whether the partial light
beams generated from the light passing through the first lens 4121 are
incident on the second lens 4131 corresponding to the first lens 4121.
That is, when the partial light beams generated from the light irradiated
from a certain position in the light emitting portion D are incident on
the corresponding second lens 4131, substantially all the light of the
partial light beams is incident on the corresponding second lens 4131. On
the other hand, when the partial light beams generated from the light
irradiated from a certain position in the light emitting portion D are
incident on the second lens 4131 next to the corresponding second lens
4131, substantially all the light of the partial light beams is incident
on the next second lens 4131. Hence, substantially all the partial light
beams incident on the corresponding second lens 4131 are not partially
reduced by an amount of some partial light beams which are incident on
the next second lens 4131, superposing such partial light beams incident
on the corresponding second lens 4131 can illuminate the image formation
area of the liquid crystal panel 441 substantially uniformly.

[0170]Hence, even when the light emitting portion D is moved in the first
direction substantially from the middle of the electrodes 4164, 4165,
luminance unevenness on the image formation area can be reduced.

[0171]The optical unit 4 is provided with the color-separating optical
device 42 which separates the light beam irradiated from the light source
device 441 into the three color light beams of red (R), green (G) and
blue (B). The liquid crystal panels 441 (441R, 441G and 441B) are
provided for each color as the optical modulators. Provided on the
downstream of the liquid crystal panels 441 is the cross dichroic prism
445 as the color-combining optical device which combines the modulated
color light beams. Accordingly, the color reproducibility can be enhanced
and an optical image can be formed with high brightness. Also, since the
image formation area of the liquid crystal panel 441 is substantially
uniformly illuminated due to the above-described focal position of the
first lens 4121, color unevenness in the formed optical image can be
reduced. Accordingly, it is possible to reduce color unevenness, to
improve color reproducibility and to form an optical image with higher
brightness.

[0172]Hence, the projector 1 of the first exemplary embodiment can reduce
luminance unevenness on the image formation area of the liquid crystal
panel 441 and color unevenness of the projected image.

2. Second Exemplary Embodiment

[0173]A projector according to the second exemplary embodiment of the
invention will be described below.

[0174]The projector of the second exemplary embodiment has a similar
structure to that of the projector 1 of the first exemplary embodiment,
but is different in that the second lens array 413 and the polarization
converter 414 of the illumination optical device are disposed reversely.
In the description below, the same or substantially the same members
already explained above are given the same numeral references and the
description thereof will be omitted.

[0175]FIG. 11 is a schematic illustration showing focal positions in the
second direction (the horizontal direction) of first lenses 412B1 of a
first lens array 412B. FIG. 12 is a schematic illustration showing focal
positions in the first direction (the vertical direction) of the first
lenses 4121B1. FIG. 11 is a schematic illustration showing an
illumination optical device 41B seen from above. FIG. 12 is a schematic
illustration showing the illumination optical device 41B seen from a
lateral side.

[0176]The projector of the second exemplary embodiment has the similar
structure to the above-described projector 1. Specifically, the projector
herein also includes the exterior cashing 2, the projection lens 3, the
optical unit 4 and the like although not shown in the figures in detail.

[0177]The optical unit 4 includes the illumination optical device 41B, the
color-separating optical device 42, the relay optical device 43, the
electrooptical device 44 and the optical component cashing 45 that
accommodates the optical components 41 to 44 and supports the projection
lens 3 at a predetermined position in a fixed manner.

[0178]As shown in FIGS. 11 and 12, the illumination optical device 41B
includes the light source device 411, the first lens array 412B, the
second lens array 413, the polarization converter 414 and the superposing
lens 415. However, the polarization converter 414 and the second lens
array 413 are positioned reversely, which is different from the
above-described illumination optical device 41.

[0179]The first lens array 412B includes, similarly to the first lens
array 412, the first lenses 412B1 (small lenses) having a substantially
rectangular shape when seen in the illumination optical axis A direction.
The first lens 412B1 divides the light beam irradiated from the light
source device 411 into a plurality of partial light beams.

[0180]As shown in FIG. 11, the focal position in the second direction (the
horizontal direction, arrow B in FIG. 11) of the first lens 412B1 is set
in the vicinity of the polarization converter 414 on the optical axis
(the central axis of the light beam) of the partial light beam irradiated
from the first lens 412B1. More specifically, the focal position in the
second direction of the first lens 412B1 is set substantially in the
center of the corresponding polarization separating layer 4141 of the
polarization converter 414.

[0181]As shown in FIG. 12, the focal position in the first direction (the
vertical direction, arrow C in FIG. 12) of the first lens 412B1 is set in
the vicinity of the second lens array 413 on the optical axis (the
central axis of the light beam) of the partial light beam irradiated from
the first lens 412B1. More specifically, the focal position in the first
direction of the first lens 412B1 is set substantially in the center of
the corresponding second lens 4131.

[0182]The projector of the second exemplary embodiment provides the same
advantages as the above-described projector 1.

[0183]Since the focal position in the second direction (the horizontal
direction) of the first lens 412B1 is set substantially in the center of
the corresponding polarization separating layer 4141 of the polarization
converter 414, the illumination region of the light beam incident on the
polarization converter 414 via the first lens 412B1 can be small.

[0184]Accordingly, when the light emitting portion D of the light source
lamp 416 is moved in the second direction and the optical path of the
light beam irradiated from the first lens 412B1 is moved in the opposite
direction of the movement direction, the light irradiation position in
the light emitting portion D determines whether the partial light beams
generated from the light having passed through the first lens 412B1 are
incident on the light incident surface 414A of the polarization converter
414. Hence, when the partial light beams generated from the light
irradiated from a certain position in the light emitting portion D are
incident on the light incident surface 414A of the polarization converter
414, substantially all the light of the partial light beams can be
incident on the light incident surface 414A. When the partial light beams
generated from the light irradiated from a certain position in the light
emitting portion D are not incident on the light incident surface 414A of
the polarization converter 414 but incident on the light shield plate
4145, substantially all the light of the partial light beams is prevented
from being incident on the light incident surface 414A.

[0185]Hence, the image formation area of the liquid crystal panel 441 can
be substantially uniformly illuminated by the light beams incident on the
light incident surface 414A, reducing luminance unevenness on the image
formation area and thereby reducing color unevenness of the formed image.

[0186]Since the focal position in the first direction (the vertical
direction) of the first lens 412B1 is set substantially in the center of
the corresponding second lens 4131, the illumination region of the light
beam incident on the second lens 4131 via the first lens 412B1 can be
small.

[0187]Accordingly, when the light emitting portion D of the light source
lamp 416 is moved in the first direction and the optical path of the
light beam irradiated from the first lens 412B1 is moved in the opposite
direction of the movement direction, the light irradiation position in
the light emitting portion D determines whether the partial light beams
generated from the light passing through the first lens 412B1 are
incident on the corresponding second lens 4131. Hence, when the partial
light beams generated from the light irradiated from a certain position
in the light emitting portion D are incident on the corresponding second
lens 4131, substantially all the light of the partial light beams can be
incident on the corresponding second lens 4131. While, when the partial
light beams generated from the light irradiated from a certain position
in the light emitting portion D are incident on the other second lens
4131 next to the corresponding second lens 4131 in the first direction,
substantially all the light of the partial light beams can be prevented
from being incident on the corresponding second lens 4131.

[0188]Hence, the image formation area of the liquid crystal panel 441 can
be substantially uniformly illuminated by the light beam incident on the
second lens 4131 corresponding to the first lens 412B1, reducing
luminance unevenness on the image formation area and thereby reducing
color unevenness of the formed image.

3. Modifications of Exemplary Embodiments

[0189]The invention is not limited to the above-explained exemplary
embodiments, but modifications, improvements and the like are in the
scope of the invention as long as an object of the invention can be
obtained.

[0190]In the exemplary embodiments, the focal position in the second
direction of the first lens 4121, 412B1 is set substantially in the
center of the corresponding polarization separating layer 4141 of the
polarization converter 414 and the focal position in the first direction
is set substantially in the center of the corresponding second lens 4131,
but the arrangement is not limited thereto. For example, it is only
necessary that the focal position in the second direction of the first
lens is set in the vicinity of the polarization converter on the optical
axis of the light beam (the central axis of the light beam) irradiated
from the first lens and that the focal position in the first direction is
set in the vicinity of the second lens array 413 on the optical axis of
the light beam irradiated from the first lens.

[0191]In the exemplary embodiments, the projector 1 is provided with the
three liquid crystal panels 441R, 441G and 441B, but the arrangement is
not limited thereto. For example, an aspect of the invention is
applicable to a projector with two, four or more than four liquid crystal
panels. The color-combining optical device that combines color light
beams modulated by the liquid crystal panels 441 is the cross dichroic
prism 445 in the exemplary embodiments, but a plurality of dichroic
mirrors may be alternatively employed.

[0192]In the exemplary embodiments, in the plane orthogonal to the
illumination axis A, the lengthwise direction of the polarization
separating layer 4141 of the polarization converter 414 is defined as the
first direction and the direction in which the polarization separating
layer 4141 and the reflection layer 4142 are aligned is defined as the
second direction, the first direction being a vertical direction, the
second direction being a horizontal direction, the second direction being
orthogonal to the first direction, but the arrangement is not limited
thereto. For example, the first direction may be horizontal and the
second direction may be vertical.

[0193]In the exemplary embodiments, the optical unit 4 substantially has
the L shape in plan view, but the shape thereof may substantially be a U
shape in plan view.

[0194]The exemplary embodiments employ the transmissive liquid crystal
panel 441 having a light beam incident surface and a light beam
irradiation surface individually, but may employ a reflective liquid
crystal panel having a surface functioning as both of the light incident
surface and the light beam irradiation surface.

[0195]In the exemplary embodiments, the projector 1 includes the light
source device 411 having the sub reflection mirror 416A, but the
arrangement is not limited thereto. For example, a light source device
not including the sub reflection mirror may be employed.

[0196]In the exemplary embodiments, the projector 1 having the liquid
crystal panels 441 is taken as an example of the optical modulator.
However, another type of optical modulator may be employed as long as the
optical modulator forms an optical image by modulating incident light
beams in accordance with image information. For example, an aspect of the
invention is applicable to a projector using an optical modulator other
than a liquid crystal layer such as a micromirror device. When using such
optical modulator, the polarization plates 442, 444 on the light beam
incident and emitting-sides may be omitted.

[0197]In the exemplary embodiments, a front-type projector 1 that projects
an image in a direction for observing a screen is taken as an example,
but an aspect of the invention is also applicable to a rear-type
projector that projects an image in a direction opposite to the direction
for observing the screen.

[0198]An aspect of the invention is applicable to a projector and
especially to a projector including a plurality of optical modulators.

Patent applications by Kazuhiro Nishida, Matsumoto-Shi JP

Patent applications by Osamu Ishibashi, Matsumoto-Shi JP

Patent applications by SEIKO EPSON CORPORATION

Patent applications in class POLARIZER OR INTERFERENCE FILTER

Patent applications in all subclasses POLARIZER OR INTERFERENCE FILTER